Professionals dealing with gait related pathologies generally accept that a large majority of persons will, at some time in their lives, suffer some form of gait related pain or dysfunction. It is well accepted that, in the majority of case, the mechanism underlying the pathology, injury, or dysfunction is biomechanically related to the interface between the foot and the ground, during the support phase of the gait cycle.
It has been proposed that providing a device to create a proprioceptive, or internal, feedback stimulus to a wearer's foot can directly target the underlying pathology, injury or dysfunction. Such a device is disclosed in U.S. Pat. No. 5,404,659 to Burk et al. As disclosed in U.S. Pat. No. 5,404,659, an arch rehabilitative catalyst stimulates the Golgi tendon organ, which in turn, stimulates the musculoskeletal structure of the foot to rehabilitate the foot structure. The catalyst is an asymmetrically domed hump, which creates a mild to strong discomfort to initially stimulate the Golgi tendon organ.
However, it has been found that the device disclosed in U.S. Pat. No. 5,404,659 does not function as described, and that the majority of wearers find the device too uncomfortable to use. In particular, when subjected to conventional vertical compressive forces of a person walking in the range of 2.5 times body weight, the device is designed to deflect between 40% and 60% of its maximum height, and when subject to only one times a person's weight, there should be no deflection. Rather than stimulate the Golgi tendon organ to create a proprioceptive response, deflections in this range can cause sever pain to a wearer, as there is insufficient give, and the wearer is always aware of the presence of the device. In addition, as disclosed in U.S. Pat. No. 5,504,659, the device has an ideal apex height of 5.25% to 7.6% of the total foot length. A device build according to these dimensions results in an overly high arch height, and can cause severe discomfort, and possible injury, to a wearer. It is further disclosed that the absolute, non-weight bearing height of the device should be the same regardless of body weight and arch height. This is clearly wrong, since different wearers will have different comfort thresholds and arch heights.
In general, the device disclosed in U.S. Pat. No. 5,404,659 does not function as described. Wearers would find the device too hard to use successfully, and rather than stimulating a proprioceptive response, the device would cause pain and discomfort at each step. The pain engendered in the foot of a wearer would, in fact, cause the wearer to limit the pressure applied to the foot to avoid the discomfort, rather than exercising the foot by creating an imperceptible stimulation as it is stated goal.